RALEIGH – The U.S. Senate race between Democratic incumbent Kay Hagan and her Republican challenger Thom Tillis looks like it’s about to become the most expensive statewide race in North Carolina history. Or will it?

While a Charlotte Observer analysis shows that total spending in the race, including that from independent groups, is expected to top out at around $103 million, that’s actually less in inflation-adjusted expenditures per registered voter than has been spent in the two most expensive U.S. Senate races in North Carolina.

At $103 million in candidate plus independent spending, the 2014 contest comes in at $15.56 per registered voter in inflation-adjusted dollars — or third place overall.

The top spending U.S. Senate race in North Carolina was in 1984, when incumbent GOP Sen. Jesse Helms defeated then Democratic Gov. Jim Hunt. That year, the two spent $20.14 per registered voter in inflation-adjusted dollars.

The next two highest per-voter spending races also had Helms’ name on the ballot. In 1990, Helms and Democrat Harvey Gantt spent $16.11 per registered voter in 2014 dollars. In 1978, Helms and Democrat John Ingram spent $14.69 per registered voter in 2014 dollars.

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But those figures understate the differential between this year’s race and those earlier battles, because the earlier calculations include only spending by candidate committees. Excluding spending from independent groups such as super PACs, Hagan and Tillis have spent only $25.6 million in this cycle — $19.6 million by Hagan, $6 million from Tillis.

That comes out to $3.87 per registered voter — 19 percent of the spending per voter that took place in the Helms-Hunt race. Add independent expenditures — which at the time were not subjected to the same reporting requirements as today — and the earlier races were even more costly.

It’s no surprise that overall spending on competitive statewide elections would increase; North Carolina’s population has grown significantly over the past four decades, as have the number of registered voters.

When Helms and Hunt faced off 30 years ago, there were roughly 3 million registered voters in North Carolina. Today, that number has more than doubled, to 6,617,536.

The 2014 spending figures account for money spent through the end of September. Those amounts certainly will rise during the closing weeks of the campaign, and final numbers won’t be reported until weeks after the votes have been counted.

Real growth in campaign spending has come from independent groups that are not affiliated with candidates or political parties, with the 2002 McCain-Feingold campaign finance law prompting the growth of super PACs and the 2010 Citizens United and subsequent Supreme Court decisions allowing individuals and corporations more leeway to exercise their First Amendment freedoms.

A lot of national attention has focused on this year’s Senate contest, since winning the race is a key to both Republican efforts to capture a majority in that chamber and Democratic efforts to maintain partisan control.

Republicans need to pick up a net of six Senate seats to win a majority.

Barry Smith (@Barry_Smith) is an associate editor of Carolina Journal.